Field of the Disclosure
The present disclosure generally relates to a downhole isolation valve and use thereof.
Description of the Related Art
A wellbore is formed to access hydrocarbon bearing formations, e.g. crude oil and/or natural gas, by the use of drilling. Drilling is accomplished by utilizing a drill bit that is mounted on the end of a drill string. To drill the wellbore, the drill string is rotated by a top drive or rotary table on a surface platform or rig, and/or by a downhole motor mounted towards the lower end of the drill string. After drilling a first segment of the wellbore, the drill string and drill bit are removed and a section of casing is lowered into the wellbore. An annulus is thus formed between the string of casing and the formation. The casing string is cemented into the wellbore by circulating cement into the annulus defined between the outer wall of the casing and the borehole. In some instances, the casing string is not cement and retrievable. The combination of cement and casing strengthens the wellbore and facilitates the isolation of certain areas of the formation behind the casing for the production of hydrocarbons.
An isolation valve assembled as part of the casing string may be used to temporarily isolate a formation pressure below the isolation valve such that a portion of the wellbore above the isolation valve may be temporarily relieved to atmospheric pressure. Since the pressure above the isolation valve is relieved, the drill/work string can be tripped into the wellbore without wellbore pressure acting to push the string out and tripped out of the wellbore without concern for swabbing the exposed formation.